I used thunderbird while using Linux. Back to Windows now and back to Outlook. It is way more comfortable than thunderbird. Especially the search function. Outlook can search across all mailboxes whereas thunderbird can only search one mailbox at a time. This was the most annoying time waster while on thunderbird.

Searching emails across several accounts through a browser window? Good luck :-D

Outlook can search across all mailboxes whereas thunderbird can only search one mailbox at a time.

My Thunderbird seems to search across all my accounts and mailboxes.